FreeBSD/Linux Kernel Cross Reference
sys/kern/init_main.c

     /*-
      * Copyright (c) 1995 Terrence R. Lambert
      * All rights reserved.
      *
      * Copyright (c) 1982, 1986, 1989, 1991, 1992, 1993
      *      The Regents of the University of California.  All rights reserved.
      * (c) UNIX System Laboratories, Inc.
      * All or some portions of this file are derived from material licensed
      * to the University of California by American Telephone and Telegraph
     * Co. or Unix System Laboratories, Inc. and are reproduced herein with
     * the permission of UNIX System Laboratories, Inc.
     *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. All advertising materials mentioning features or use of this software
     *    must display the following acknowledgement:
     *      This product includes software developed by the University of
     *      California, Berkeley and its contributors.
     * 4. Neither the name of the University nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     *      @(#)init_main.c 8.9 (Berkeley) 1/21/94
     */
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD: releng/10.1/sys/kern/init_main.c 255708 2013-09-19 18:53:42Z jhb $");
    
    #include "opt_ddb.h"
    #include "opt_init_path.h"
    
    #include <sys/param.h>
    #include <sys/kernel.h>
    #include <sys/exec.h>
    #include <sys/file.h>
    #include <sys/filedesc.h>
    #include <sys/jail.h>
    #include <sys/ktr.h>
    #include <sys/lock.h>
    #include <sys/loginclass.h>
    #include <sys/mount.h>
    #include <sys/mutex.h>
    #include <sys/syscallsubr.h>
    #include <sys/sysctl.h>
    #include <sys/proc.h>
    #include <sys/racct.h>
    #include <sys/resourcevar.h>
    #include <sys/systm.h>
    #include <sys/signalvar.h>
    #include <sys/vnode.h>
    #include <sys/sysent.h>
    #include <sys/reboot.h>
    #include <sys/sched.h>
    #include <sys/sx.h>
    #include <sys/sysproto.h>
    #include <sys/vmmeter.h>
    #include <sys/unistd.h>
    #include <sys/malloc.h>
    #include <sys/conf.h>
    #include <sys/cpuset.h>
    
    #include <machine/cpu.h>
    
    #include <security/audit/audit.h>
    #include <security/mac/mac_framework.h>
    
    #include <vm/vm.h>
    #include <vm/vm_param.h>
    #include <vm/pmap.h>
    #include <vm/vm_map.h>
    #include <sys/copyright.h>
    
    #include <ddb/ddb.h>
    #include <ddb/db_sym.h>
    
    void mi_startup(void);                          /* Should be elsewhere */
    
    /* Components of the first process -- never freed. */
    static struct session session0;
    static struct pgrp pgrp0;
    struct  proc proc0;
   struct  thread thread0 __aligned(16);
   struct  vmspace vmspace0;
   struct  proc *initproc;
   
   #ifndef BOOTHOWTO
   #define BOOTHOWTO       0
   #endif
   int     boothowto = BOOTHOWTO;  /* initialized so that it can be patched */
   SYSCTL_INT(_debug, OID_AUTO, boothowto, CTLFLAG_RD, &boothowto, 0,
           "Boot control flags, passed from loader");
   
   #ifndef BOOTVERBOSE
   #define BOOTVERBOSE     0
   #endif
   int     bootverbose = BOOTVERBOSE;
   SYSCTL_INT(_debug, OID_AUTO, bootverbose, CTLFLAG_RW, &bootverbose, 0,
           "Control the output of verbose kernel messages");
   
   /*
    * This ensures that there is at least one entry so that the sysinit_set
    * symbol is not undefined.  A sybsystem ID of SI_SUB_DUMMY is never
    * executed.
    */
   SYSINIT(placeholder, SI_SUB_DUMMY, SI_ORDER_ANY, NULL, NULL);
   
   /*
    * The sysinit table itself.  Items are checked off as the are run.
    * If we want to register new sysinit types, add them to newsysinit.
    */
   SET_DECLARE(sysinit_set, struct sysinit);
   struct sysinit **sysinit, **sysinit_end;
   struct sysinit **newsysinit, **newsysinit_end;
   
   /*
    * Merge a new sysinit set into the current set, reallocating it if
    * necessary.  This can only be called after malloc is running.
    */
   void
   sysinit_add(struct sysinit **set, struct sysinit **set_end)
   {
           struct sysinit **newset;
           struct sysinit **sipp;
           struct sysinit **xipp;
           int count;
   
           count = set_end - set;
           if (newsysinit)
                   count += newsysinit_end - newsysinit;
           else
                   count += sysinit_end - sysinit;
           newset = malloc(count * sizeof(*sipp), M_TEMP, M_NOWAIT);
           if (newset == NULL)
                   panic("cannot malloc for sysinit");
           xipp = newset;
           if (newsysinit)
                   for (sipp = newsysinit; sipp < newsysinit_end; sipp++)
                           *xipp++ = *sipp;
           else
                   for (sipp = sysinit; sipp < sysinit_end; sipp++)
                           *xipp++ = *sipp;
           for (sipp = set; sipp < set_end; sipp++)
                   *xipp++ = *sipp;
           if (newsysinit)
                   free(newsysinit, M_TEMP);
           newsysinit = newset;
           newsysinit_end = newset + count;
   }
   
   #if defined (DDB) && defined(VERBOSE_SYSINIT)
   static const char *
   symbol_name(vm_offset_t va, db_strategy_t strategy)
   {
           const char *name;
           c_db_sym_t sym;
           db_expr_t  offset;
   
           if (va == 0)
                   return (NULL);
           sym = db_search_symbol(va, strategy, &offset);
           if (offset != 0)
                   return (NULL);
           db_symbol_values(sym, &name, NULL);
           return (name);
   }
   #endif
   
   /*
    * System startup; initialize the world, create process 0, mount root
    * filesystem, and fork to create init and pagedaemon.  Most of the
    * hard work is done in the lower-level initialization routines including
    * startup(), which does memory initialization and autoconfiguration.
    *
    * This allows simple addition of new kernel subsystems that require
    * boot time initialization.  It also allows substitution of subsystem
    * (for instance, a scheduler, kernel profiler, or VM system) by object
    * module.  Finally, it allows for optional "kernel threads".
    */
   void
   mi_startup(void)
   {
   
           register struct sysinit **sipp;         /* system initialization*/
           register struct sysinit **xipp;         /* interior loop of sort*/
           register struct sysinit *save;          /* bubble*/
   
   #if defined(VERBOSE_SYSINIT)
           int last;
           int verbose;
   #endif
   
           if (boothowto & RB_VERBOSE)
                   bootverbose++;
   
           if (sysinit == NULL) {
                   sysinit = SET_BEGIN(sysinit_set);
                   sysinit_end = SET_LIMIT(sysinit_set);
           }
   
   restart:
           /*
            * Perform a bubble sort of the system initialization objects by
            * their subsystem (primary key) and order (secondary key).
            */
           for (sipp = sysinit; sipp < sysinit_end; sipp++) {
                   for (xipp = sipp + 1; xipp < sysinit_end; xipp++) {
                           if ((*sipp)->subsystem < (*xipp)->subsystem ||
                                ((*sipp)->subsystem == (*xipp)->subsystem &&
                                 (*sipp)->order <= (*xipp)->order))
                                   continue;       /* skip*/
                           save = *sipp;
                           *sipp = *xipp;
                           *xipp = save;
                   }
           }
   
   #if defined(VERBOSE_SYSINIT)
           last = SI_SUB_COPYRIGHT;
           verbose = 0;
   #if !defined(DDB)
           printf("VERBOSE_SYSINIT: DDB not enabled, symbol lookups disabled.\n");
   #endif
   #endif
   
           /*
            * Traverse the (now) ordered list of system initialization tasks.
            * Perform each task, and continue on to the next task.
            */
           for (sipp = sysinit; sipp < sysinit_end; sipp++) {
   
                   if ((*sipp)->subsystem == SI_SUB_DUMMY)
                           continue;       /* skip dummy task(s)*/
   
                   if ((*sipp)->subsystem == SI_SUB_DONE)
                           continue;
   
   #if defined(VERBOSE_SYSINIT)
                   if ((*sipp)->subsystem > last) {
                           verbose = 1;
                           last = (*sipp)->subsystem;
                           printf("subsystem %x\n", last);
                   }
                   if (verbose) {
   #if defined(DDB)
                           const char *func, *data;
   
                           func = symbol_name((vm_offset_t)(*sipp)->func,
                               DB_STGY_PROC);
                           data = symbol_name((vm_offset_t)(*sipp)->udata,
                               DB_STGY_ANY);
                           if (func != NULL && data != NULL)
                                   printf("   %s(&%s)... ", func, data);
                           else if (func != NULL)
                                   printf("   %s(%p)... ", func, (*sipp)->udata);
                           else
   #endif
                                   printf("   %p(%p)... ", (*sipp)->func,
                                       (*sipp)->udata);
                   }
   #endif
   
                   /* Call function */
                   (*((*sipp)->func))((*sipp)->udata);
   
   #if defined(VERBOSE_SYSINIT)
                   if (verbose)
                           printf("done.\n");
   #endif
   
                   /* Check off the one we're just done */
                   (*sipp)->subsystem = SI_SUB_DONE;
   
                   /* Check if we've installed more sysinit items via KLD */
                   if (newsysinit != NULL) {
                           if (sysinit != SET_BEGIN(sysinit_set))
                                   free(sysinit, M_TEMP);
                           sysinit = newsysinit;
                           sysinit_end = newsysinit_end;
                           newsysinit = NULL;
                           newsysinit_end = NULL;
                           goto restart;
                   }
           }
   
           mtx_assert(&Giant, MA_OWNED | MA_NOTRECURSED);
           mtx_unlock(&Giant);
   
           /*
            * Now hand over this thread to swapper.
            */
           swapper();
           /* NOTREACHED*/
   }
   
   
   /*
    ***************************************************************************
    ****
    **** The following SYSINIT's belong elsewhere, but have not yet
    **** been moved.
    ****
    ***************************************************************************
    */
   static void
   print_caddr_t(void *data)
   {
           printf("%s", (char *)data);
   }
   
   static void
   print_version(void *data __unused)
   {
           int len;
   
           /* Strip a trailing newline from version. */
           len = strlen(version);
           while (len > 0 && version[len - 1] == '\n')
                   len--;
           printf("%.*s %s\n", len, version, machine);
           printf("%s\n", compiler_version);
   }
   
   SYSINIT(announce, SI_SUB_COPYRIGHT, SI_ORDER_FIRST, print_caddr_t,
       copyright);
   SYSINIT(trademark, SI_SUB_COPYRIGHT, SI_ORDER_SECOND, print_caddr_t,
       trademark);
   SYSINIT(version, SI_SUB_COPYRIGHT, SI_ORDER_THIRD, print_version, NULL);
   
   #ifdef WITNESS
   static char wit_warn[] =
        "WARNING: WITNESS option enabled, expect reduced performance.\n";
   SYSINIT(witwarn, SI_SUB_COPYRIGHT, SI_ORDER_THIRD + 1,
      print_caddr_t, wit_warn);
   SYSINIT(witwarn2, SI_SUB_LAST, SI_ORDER_THIRD + 1,
      print_caddr_t, wit_warn);
   #endif
   
   #ifdef DIAGNOSTIC
   static char diag_warn[] =
        "WARNING: DIAGNOSTIC option enabled, expect reduced performance.\n";
   SYSINIT(diagwarn, SI_SUB_COPYRIGHT, SI_ORDER_THIRD + 2,
       print_caddr_t, diag_warn);
   SYSINIT(diagwarn2, SI_SUB_LAST, SI_ORDER_THIRD + 2,
       print_caddr_t, diag_warn);
   #endif
   
   static int
   null_fetch_syscall_args(struct thread *td __unused,
       struct syscall_args *sa __unused)
   {
   
           panic("null_fetch_syscall_args");
   }
   
   static void
   null_set_syscall_retval(struct thread *td __unused, int error __unused)
   {
   
           panic("null_set_syscall_retval");
   }
   
   struct sysentvec null_sysvec = {
           .sv_size        = 0,
           .sv_table       = NULL,
           .sv_mask        = 0,
           .sv_sigsize     = 0,
           .sv_sigtbl      = NULL,
           .sv_errsize     = 0,
           .sv_errtbl      = NULL,
           .sv_transtrap   = NULL,
           .sv_fixup       = NULL,
           .sv_sendsig     = NULL,
           .sv_sigcode     = NULL,
           .sv_szsigcode   = NULL,
           .sv_prepsyscall = NULL,
           .sv_name        = "null",
           .sv_coredump    = NULL,
           .sv_imgact_try  = NULL,
           .sv_minsigstksz = 0,
           .sv_pagesize    = PAGE_SIZE,
           .sv_minuser     = VM_MIN_ADDRESS,
           .sv_maxuser     = VM_MAXUSER_ADDRESS,
           .sv_usrstack    = USRSTACK,
           .sv_psstrings   = PS_STRINGS,
           .sv_stackprot   = VM_PROT_ALL,
           .sv_copyout_strings     = NULL,
           .sv_setregs     = NULL,
           .sv_fixlimit    = NULL,
           .sv_maxssiz     = NULL,
           .sv_flags       = 0,
           .sv_set_syscall_retval = null_set_syscall_retval,
           .sv_fetch_syscall_args = null_fetch_syscall_args,
           .sv_syscallnames = NULL,
           .sv_schedtail   = NULL,
   };
   
   /*
    ***************************************************************************
    ****
    **** The two following SYSINIT's are proc0 specific glue code.  I am not
    **** convinced that they can not be safely combined, but their order of
    **** operation has been maintained as the same as the original init_main.c
    **** for right now.
    ****
    **** These probably belong in init_proc.c or kern_proc.c, since they
    **** deal with proc0 (the fork template process).
    ****
    ***************************************************************************
    */
   /* ARGSUSED*/
   static void
   proc0_init(void *dummy __unused)
   {
           struct proc *p;
           struct thread *td;
           vm_paddr_t pageablemem;
           int i;
   
           GIANT_REQUIRED;
           p = &proc0;
           td = &thread0;
           
           /*
            * Initialize magic number and osrel.
            */
           p->p_magic = P_MAGIC;
           p->p_osrel = osreldate;
   
           /*
            * Initialize thread and process structures.
            */
           procinit();     /* set up proc zone */
           threadinit();   /* set up UMA zones */
   
           /*
            * Initialise scheduler resources.
            * Add scheduler specific parts to proc, thread as needed.
            */
           schedinit();    /* scheduler gets its house in order */
   
           /*
            * Create process 0 (the swapper).
            */
           LIST_INSERT_HEAD(&allproc, p, p_list);
           LIST_INSERT_HEAD(PIDHASH(0), p, p_hash);
           mtx_init(&pgrp0.pg_mtx, "process group", NULL, MTX_DEF | MTX_DUPOK);
           p->p_pgrp = &pgrp0;
           LIST_INSERT_HEAD(PGRPHASH(0), &pgrp0, pg_hash);
           LIST_INIT(&pgrp0.pg_members);
           LIST_INSERT_HEAD(&pgrp0.pg_members, p, p_pglist);
   
           pgrp0.pg_session = &session0;
           mtx_init(&session0.s_mtx, "session", NULL, MTX_DEF);
           refcount_init(&session0.s_count, 1);
           session0.s_leader = p;
   
           p->p_sysent = &null_sysvec;
           p->p_flag = P_SYSTEM | P_INMEM;
           p->p_flag2 = 0;
           p->p_state = PRS_NORMAL;
           knlist_init_mtx(&p->p_klist, &p->p_mtx);
           STAILQ_INIT(&p->p_ktr);
           p->p_nice = NZERO;
           /* pid_max cannot be greater than PID_MAX */
           td->td_tid = PID_MAX + 1;
           LIST_INSERT_HEAD(TIDHASH(td->td_tid), td, td_hash);
           td->td_state = TDS_RUNNING;
           td->td_pri_class = PRI_TIMESHARE;
           td->td_user_pri = PUSER;
           td->td_base_user_pri = PUSER;
           td->td_lend_user_pri = PRI_MAX;
           td->td_priority = PVM;
           td->td_base_pri = PVM;
           td->td_oncpu = 0;
           td->td_flags = TDF_INMEM;
           td->td_pflags = TDP_KTHREAD;
           td->td_cpuset = cpuset_thread0();
           prison0.pr_cpuset = cpuset_ref(td->td_cpuset);
           p->p_peers = 0;
           p->p_leader = p;
   
   
           strncpy(p->p_comm, "kernel", sizeof (p->p_comm));
           strncpy(td->td_name, "swapper", sizeof (td->td_name));
   
           callout_init_mtx(&p->p_itcallout, &p->p_mtx, 0);
           callout_init_mtx(&p->p_limco, &p->p_mtx, 0);
           callout_init(&td->td_slpcallout, CALLOUT_MPSAFE);
   
           /* Create credentials. */
           p->p_ucred = crget();
           p->p_ucred->cr_ngroups = 1;     /* group 0 */
           p->p_ucred->cr_uidinfo = uifind(0);
           p->p_ucred->cr_ruidinfo = uifind(0);
           p->p_ucred->cr_prison = &prison0;
           p->p_ucred->cr_loginclass = loginclass_find("default");
   #ifdef AUDIT
           audit_cred_kproc0(p->p_ucred);
   #endif
   #ifdef MAC
           mac_cred_create_swapper(p->p_ucred);
   #endif
           td->td_ucred = crhold(p->p_ucred);
   
           /* Create sigacts. */
           p->p_sigacts = sigacts_alloc();
   
           /* Initialize signal state for process 0. */
           siginit(&proc0);
   
           /* Create the file descriptor table. */
           p->p_fd = fdinit(NULL);
           p->p_fdtol = NULL;
   
           /* Create the limits structures. */
           p->p_limit = lim_alloc();
           for (i = 0; i < RLIM_NLIMITS; i++)
                   p->p_limit->pl_rlimit[i].rlim_cur =
                       p->p_limit->pl_rlimit[i].rlim_max = RLIM_INFINITY;
           p->p_limit->pl_rlimit[RLIMIT_NOFILE].rlim_cur =
               p->p_limit->pl_rlimit[RLIMIT_NOFILE].rlim_max = maxfiles;
           p->p_limit->pl_rlimit[RLIMIT_NPROC].rlim_cur =
               p->p_limit->pl_rlimit[RLIMIT_NPROC].rlim_max = maxproc;
           p->p_limit->pl_rlimit[RLIMIT_DATA].rlim_cur = dfldsiz;
           p->p_limit->pl_rlimit[RLIMIT_DATA].rlim_max = maxdsiz;
           p->p_limit->pl_rlimit[RLIMIT_STACK].rlim_cur = dflssiz;
           p->p_limit->pl_rlimit[RLIMIT_STACK].rlim_max = maxssiz;
           /* Cast to avoid overflow on i386/PAE. */
           pageablemem = ptoa((vm_paddr_t)cnt.v_free_count);
           p->p_limit->pl_rlimit[RLIMIT_RSS].rlim_cur =
               p->p_limit->pl_rlimit[RLIMIT_RSS].rlim_max = pageablemem;
           p->p_limit->pl_rlimit[RLIMIT_MEMLOCK].rlim_cur = pageablemem / 3;
           p->p_limit->pl_rlimit[RLIMIT_MEMLOCK].rlim_max = pageablemem;
           p->p_cpulimit = RLIM_INFINITY;
   
           /* Initialize resource accounting structures. */
           racct_create(&p->p_racct);
   
           p->p_stats = pstats_alloc();
   
           /* Allocate a prototype map so we have something to fork. */
           pmap_pinit0(vmspace_pmap(&vmspace0));
           p->p_vmspace = &vmspace0;
           vmspace0.vm_refcnt = 1;
   
           /*
            * proc0 is not expected to enter usermode, so there is no special
            * handling for sv_minuser here, like is done for exec_new_vmspace().
            */
           vm_map_init(&vmspace0.vm_map, vmspace_pmap(&vmspace0),
               p->p_sysent->sv_minuser, p->p_sysent->sv_maxuser);
   
           /*
            * Call the init and ctor for the new thread and proc.  We wait
            * to do this until all other structures are fairly sane.
            */
           EVENTHANDLER_INVOKE(process_init, p);
           EVENTHANDLER_INVOKE(thread_init, td);
           EVENTHANDLER_INVOKE(process_ctor, p);
           EVENTHANDLER_INVOKE(thread_ctor, td);
   
           /*
            * Charge root for one process.
            */
           (void)chgproccnt(p->p_ucred->cr_ruidinfo, 1, 0);
           PROC_LOCK(p);
           racct_add_force(p, RACCT_NPROC, 1);
           PROC_UNLOCK(p);
   }
   SYSINIT(p0init, SI_SUB_INTRINSIC, SI_ORDER_FIRST, proc0_init, NULL);
   
   /* ARGSUSED*/
   static void
   proc0_post(void *dummy __unused)
   {
           struct timespec ts;
           struct proc *p;
           struct rusage ru;
           struct thread *td;
   
           /*
            * Now we can look at the time, having had a chance to verify the
            * time from the filesystem.  Pretend that proc0 started now.
            */
           sx_slock(&allproc_lock);
           FOREACH_PROC_IN_SYSTEM(p) {
                   microuptime(&p->p_stats->p_start);
                   PROC_SLOCK(p);
                   rufetch(p, &ru);        /* Clears thread stats */
                   PROC_SUNLOCK(p);
                   p->p_rux.rux_runtime = 0;
                   p->p_rux.rux_uticks = 0;
                   p->p_rux.rux_sticks = 0;
                   p->p_rux.rux_iticks = 0;
                   FOREACH_THREAD_IN_PROC(p, td) {
                           td->td_runtime = 0;
                   }
           }
           sx_sunlock(&allproc_lock);
           PCPU_SET(switchtime, cpu_ticks());
           PCPU_SET(switchticks, ticks);
   
           /*
            * Give the ``random'' number generator a thump.
            */
           nanotime(&ts);
           srandom(ts.tv_sec ^ ts.tv_nsec);
   }
   SYSINIT(p0post, SI_SUB_INTRINSIC_POST, SI_ORDER_FIRST, proc0_post, NULL);
   
   static void
   random_init(void *dummy __unused)
   {
   
           /*
            * After CPU has been started we have some randomness on most
            * platforms via get_cyclecount().  For platforms that don't
            * we will reseed random(9) in proc0_post() as well.
            */
           srandom(get_cyclecount());
   }
   SYSINIT(random, SI_SUB_RANDOM, SI_ORDER_FIRST, random_init, NULL);
   
   /*
    ***************************************************************************
    ****
    **** The following SYSINIT's and glue code should be moved to the
    **** respective files on a per subsystem basis.
    ****
    ***************************************************************************
    */
   
   
   /*
    ***************************************************************************
    ****
    **** The following code probably belongs in another file, like
    **** kern/init_init.c.
    ****
    ***************************************************************************
    */
   
   /*
    * List of paths to try when searching for "init".
    */
   static char init_path[MAXPATHLEN] =
   #ifdef  INIT_PATH
       __XSTRING(INIT_PATH);
   #else
       "/sbin/init:/sbin/oinit:/sbin/init.bak:/rescue/init";
   #endif
   SYSCTL_STRING(_kern, OID_AUTO, init_path, CTLFLAG_RD, init_path, 0,
           "Path used to search the init process");
   
   /*
    * Shutdown timeout of init(8).
    * Unused within kernel, but used to control init(8), hence do not remove.
    */
   #ifndef INIT_SHUTDOWN_TIMEOUT
   #define INIT_SHUTDOWN_TIMEOUT 120
   #endif
   static int init_shutdown_timeout = INIT_SHUTDOWN_TIMEOUT;
   SYSCTL_INT(_kern, OID_AUTO, init_shutdown_timeout,
           CTLFLAG_RW, &init_shutdown_timeout, 0, "Shutdown timeout of init(8). "
           "Unused within kernel, but used to control init(8)");
   
   /*
    * Start the initial user process; try exec'ing each pathname in init_path.
    * The program is invoked with one argument containing the boot flags.
    */
   static void
   start_init(void *dummy)
   {
           vm_offset_t addr;
           struct execve_args args;
           int options, error;
           char *var, *path, *next, *s;
           char *ucp, **uap, *arg0, *arg1;
           struct thread *td;
           struct proc *p;
   
           mtx_lock(&Giant);
   
           GIANT_REQUIRED;
   
           td = curthread;
           p = td->td_proc;
   
           vfs_mountroot();
   
           /*
            * Need just enough stack to hold the faked-up "execve()" arguments.
            */
           addr = p->p_sysent->sv_usrstack - PAGE_SIZE;
           if (vm_map_find(&p->p_vmspace->vm_map, NULL, 0, &addr, PAGE_SIZE, 0,
               VMFS_NO_SPACE, VM_PROT_ALL, VM_PROT_ALL, 0) != 0)
                   panic("init: couldn't allocate argument space");
           p->p_vmspace->vm_maxsaddr = (caddr_t)addr;
           p->p_vmspace->vm_ssize = 1;
   
           if ((var = getenv("init_path")) != NULL) {
                   strlcpy(init_path, var, sizeof(init_path));
                   freeenv(var);
           }
           
           for (path = init_path; *path != '\0'; path = next) {
                   while (*path == ':')
                           path++;
                   if (*path == '\0')
                           break;
                   for (next = path; *next != '\0' && *next != ':'; next++)
                           /* nothing */ ;
                   if (bootverbose)
                           printf("start_init: trying %.*s\n", (int)(next - path),
                               path);
                           
                   /*
                    * Move out the boot flag argument.
                    */
                   options = 0;
                   ucp = (char *)p->p_sysent->sv_usrstack;
                   (void)subyte(--ucp, 0);         /* trailing zero */
                   if (boothowto & RB_SINGLE) {
                           (void)subyte(--ucp, 's');
                           options = 1;
                   }
   #ifdef notyet
                   if (boothowto & RB_FASTBOOT) {
                           (void)subyte(--ucp, 'f');
                           options = 1;
                   }
   #endif
   
   #ifdef BOOTCDROM
                   (void)subyte(--ucp, 'C');
                   options = 1;
   #endif
   
                   if (options == 0)
                           (void)subyte(--ucp, '-');
                   (void)subyte(--ucp, '-');               /* leading hyphen */
                   arg1 = ucp;
   
                   /*
                    * Move out the file name (also arg 0).
                    */
                   (void)subyte(--ucp, 0);
                   for (s = next - 1; s >= path; s--)
                           (void)subyte(--ucp, *s);
                   arg0 = ucp;
   
                   /*
                    * Move out the arg pointers.
                    */
                   uap = (char **)((intptr_t)ucp & ~(sizeof(intptr_t)-1));
                   (void)suword((caddr_t)--uap, (long)0);  /* terminator */
                   (void)suword((caddr_t)--uap, (long)(intptr_t)arg1);
                   (void)suword((caddr_t)--uap, (long)(intptr_t)arg0);
   
                   /*
                    * Point at the arguments.
                    */
                   args.fname = arg0;
                   args.argv = uap;
                   args.envv = NULL;
   
                   /*
                    * Now try to exec the program.  If can't for any reason
                    * other than it doesn't exist, complain.
                    *
                    * Otherwise, return via fork_trampoline() all the way
                    * to user mode as init!
                    */
                   if ((error = sys_execve(td, &args)) == 0) {
                           mtx_unlock(&Giant);
                           return;
                   }
                   if (error != ENOENT)
                           printf("exec %.*s: error %d\n", (int)(next - path), 
                               path, error);
           }
           printf("init: not found in path %s\n", init_path);
           panic("no init");
   }
   
   /*
    * Like kproc_create(), but runs in it's own address space.
    * We do this early to reserve pid 1.
    *
    * Note special case - do not make it runnable yet.  Other work
    * in progress will change this more.
    */
   static void
   create_init(const void *udata __unused)
   {
           struct ucred *newcred, *oldcred;
           int error;
   
           error = fork1(&thread0, RFFDG | RFPROC | RFSTOPPED, 0, &initproc,
               NULL, 0);
           if (error)
                   panic("cannot fork init: %d\n", error);
           KASSERT(initproc->p_pid == 1, ("create_init: initproc->p_pid != 1"));
           /* divorce init's credentials from the kernel's */
           newcred = crget();
           PROC_LOCK(initproc);
           initproc->p_flag |= P_SYSTEM | P_INMEM;
           oldcred = initproc->p_ucred;
           crcopy(newcred, oldcred);
   #ifdef MAC
           mac_cred_create_init(newcred);
   #endif
   #ifdef AUDIT
           audit_cred_proc1(newcred);
   #endif
           initproc->p_ucred = newcred;
           PROC_UNLOCK(initproc);
           crfree(oldcred);
           cred_update_thread(FIRST_THREAD_IN_PROC(initproc));
           cpu_set_fork_handler(FIRST_THREAD_IN_PROC(initproc), start_init, NULL);
   }
   SYSINIT(init, SI_SUB_CREATE_INIT, SI_ORDER_FIRST, create_init, NULL);
   
   /*
    * Make it runnable now.
    */
   static void
   kick_init(const void *udata __unused)
   {
           struct thread *td;
   
           td = FIRST_THREAD_IN_PROC(initproc);
           thread_lock(td);
           TD_SET_CAN_RUN(td);
           sched_add(td, SRQ_BORING);
           thread_unlock(td);
   }
   SYSINIT(kickinit, SI_SUB_KTHREAD_INIT, SI_ORDER_FIRST, kick_init, NULL);

Cache object: a90dabf2c450e2beabbdbc904eb2c316